Studies on fluorescence and photosensitization in aqueous solution. II.―Fluorescence in aqueous solution

Abstract

In the present work we have attempted to make a general systematic survey of the effect of the addition of salts to fluorescent solutions. The effect of the presence of salts on fluorescent solutions was noticed by the earliest workers on the subject; Stokes, for instance, reports that while solutions of quinine in sulphuric, nitric, tartaric, succinic and phosphoric acid were fluorescent, the addition of the halogen hydracids and of sodium chloride extinguished the fluorescence. Similar observations were made by Buckingham! and recently by Desha, Sherrill and Harrison. Apparatus .—We chose as measuring instrument the photoelectric cell. After preliminary experiments had shown that the inconstancy of the light source made it troublesome and inaccurate to measure the current from a single photo-cell illuminated directly by the fluorescent light, we finally adopted a differential method, the essentials of which are sketched below.